Support structure constructed from hollow members, more particularly tubes of thin hard-rolled metal sheets



I Nov. 10, 1959 J. PFISTERSHAMMER SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBERS, MORE PARTICULARLY TUBES OF THIN HARD-ROLLED METAL SHEETS Filed March 29, 1954 I HIHHHI H fillllillH lllllllllu 6 Sheets-Sheet 1 I .Z 1% FIG? :5

FIG. [3

AAAAA AVAVAIAV V V V V U Q N 1959 J. PFISTERSHAMMER 2 SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBERS, MORE PARTICULARLY TUBES OF THIN HARD-ROLLED METAL SHEETS Filed March 29, 1954 6 Sheets-Sheet 2 .5 4 FIG.I5 FIG.I6 FIG.|7 V

Nov. 10, 1959 J. PFISTERSHAMMER 2,912,075

SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBERS. MORE PARTICULARLY TUBES 0F THIN HARD-ROLLED METAL SHEETS Filed March 29, 1954 6 Sheets-Sheet 3 FIG. 24'

6/ FIG. 26 6/ 6 FIG. 25

FIG.28 6;

2,912,075 RS. MORE SHEETS 1959 J. PFISTERSHAMMER SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBE PARTICULARLY TUBES 0F Filed March 29, 1954 THIN HARD-ROLLED METAL 6 Sheets-Sheet 4 F l G. 3|

F l G. 30

.1. PFISTERSHAMMER 2,912,075

S, MORE TAL SHEETS Nov. 10, 1959 SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBER PARTICULARLY TUBES OF THIN HARD-ROLLED ME Filed March 29, 1954 6 Sheets-Sheet 5 FIG. 42

FIG. 43

FIG. 36

FIG.

FIG. 39

FIG. 38

2,912,075 s. MORE SHEETS 1959 J. PFISTERSHAMMER SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBER PARTICULARLY TUBES OF THIN HARD-ROLLED METAL Filed March 29, 1954 6 Sheets-Sheet 6 FIG. 4|

United States SUPPORT STRUCTURE CONSTRUCTED FROM HOLLOW MEMBERS, MORE PARTICULARLY TUBES F THIN HARD-ROLLED METAL SHEETS Josef Pfistershammer, Chain, Switzerland Application March 29, 1954, Serial No. 419,541

Claims priority, application Switzerland March 28, 1953 17 Claims. (Cl. 189-26) It is known to construct support structures, such as hall constructions, scaffolding, pylons, drilling towers, aircraft, wagon and other vehicle constructions etc. from self-supporting hollow members and from tubular constructions. Drawn or welded tubes are generally used whose wall thickness is in a similar ratio in proportion to the diameter thereof as in the case of normal gas pipes, Water pipes and Mannesmann pipes. The connection together of the individual tubes for their extension and to form nodes (strengthening joints) is effected by direct welding or by means of welded, riveted or soldered end pieces, which are then connected by bolts. Such tube constructions require a great deal of constructional material and have a great weight. They are expensive to produce, to transport and to assemble. The great weight requires relatively considerable foundations and produces high rocking moments particularly in the case of drilling towers and pylons.

The support structures according to the present invention are produced with especially thin-walls and from particularly hard material, in cylindrical, conical or spindle shaped forms of round, elliptical or other appropriate cross-section so that the buckling strength of all bars or parts which are subjected to pressure is constantly adapted to the increasing and decreasing buckling moments within each bar. The cutting of the material for conical and spindle shaped tubes can be effected without Waste. The tube walls consisting of one or more parts are rounded after the cutting, and their longitudinal edges for the longitudinal seams and the end edges for the annular seams are then provided with connecting tongues, which during cutting and bending are fashioned in an arcuate shape, are arranged preferably in parallel groups and are only brought into a more angular shape when closing the seam by pressure and upsetting. [Moreover, in order to produce connections resistant to traction, pressure and distortion, the ends of the thin-walled tubes are provided with connecting tubes, with shaped portions in the walls of the tubes operative transversely to the direction of. force, and with connecting means which fit into the said shaped portions, fill them, and clamp the thin tube walls over a large surface thereof without reducing the cross-section of the said tubes.

In order to fix any desired parts in any desired position on the thin tube walls or supporting sheet metal shells, the thin sheet metal wall is provided with further shaped portions which extend transversely to the forces occurring. The connecting members provided have contact surfaces which are provided with raised portions and recesses which fit into the sheet metal or tube wall, and a large surface of the tube Wall can be reliably clamped between the said elevations and recesses.

Such support structures avoid the disadvantages of those which have hitherto been known. No heat treatment reduces the strength of the parts. They are simple and cheap to produce, may be transported satisfactorily and cheaply in parts and can be easily and quickly assembled. Weight and buckling moments are extremely small;

2,912,075 Patented Nov. 10, 1959 owing to the conical and spindle shaped form of the tubes, and by re-inforcing filling elements which may be arranged, and the shaping of the connecting means according to the invention, the surface exposed to the wind is reduced and the cross-section is continually adapted to the forces occurring. This results in cheapness and great security with the use of the smallest possible stress on the foundations and the greatest reliability of operation, while avoiding local material fatigue.

Several constructional examples of the invention are shown in the drawings:

Fig. 1 shows the cutting up of the tubes without leaving any waste,

Figs. 2, 3 and 4 show the production of a round tube from a wall portion,

Figs. 5, 6 and 7 show the production of an elliptical tube from a wall portion,

Figs. 8, 9, 10, 11 and 12 show the production of a round conical tube from two wall parts,

Fig. 13 is a diagrammatic view of a tool for cutting and giving an arcuate shape to the connecting tongues for particularly hard sheets of metal,

Fig. 14 is a plan view of an improved locking-seam,

Fig. 15 shows a section A-B through Fig. 14,

Figs. 16 and 17 are sectional views of two metal strips with the improved locking seam according to Fig. 15, pushed into each other and closed,

Fig. 18 shows two conical tubes with a two-row locking seam connected in their longitudinal direction,

Fig. 19 shows a spindle shaped tube with a double connecting-locking seam in the middle of the tube and with an end piece for the connection of a strut to a node,

Fig. 20 shows asection through a plain annular tube connection, 7 I

Fig. 21 is a partly sectional view of an annular tube connection with two inner rings,

Fig. 22 shows a part section through an annular tube connection which is stepped as viewed in cross-section,

Fig. 23 is a plan view according to Fig. 22,

clamping bolts,

Figs. 25 and 26 show the two ends of a clamping ring provided with inclined teeth, with a locking device,

Figs. 27 and 28 show the two ends of'a clamping ring with angular toothing engaging over one another,

Fig. 29 shows a spindle shaped tube with tube connections in the middle and at the end,

Fig. 30 shows the construction of a support structure from spindle shaped tubes with connections according to the invention,

Fig. 31 shows a cross-section through a force node of Fig. 30, taken in the line GH,

Fig. 32 is a view of a force node .of Fig. 30 which at the same time serves for fixing a transverse support,

Figs. 33, 34 and 35 show two riveted connections and one bolt connection-with corrugated shaped portions of the tube wall, the corrugations terminating before the edges of the zone of connection, a v

Fig. 36 is a cross-section taken on the line I-K in Fig. 37 through a joint with a strengthening member which has four pairs of clamping surfaces and four different types of clamping,

Fig. 37 shows the same connection in a side View,

Fig. 38 shows a strengthening element with six pairs of clamping surfaces,

Fig. 39 shows a triangular strengthening element,

Fig. 40 shows a force node with three connected cross struts, in a side view, 1

Fig. 41 is a sectional view taken on the line L.M of Fig. 40,

Fig. 42 is a section through the forked end of a cross strut,

"waste. "developments the conicity of the tube development is Fig. 43 is a section through the plain end of a cross strut,

Fig. 44 is a plan view of the same end,

Fig. 45 is a section taken on the line N-O of Fig. 44,

Fig. 46 is a section through a joint wherein a tubular element is inserted as a strengthening member in the two adjoining tubes.

According to the invention the support structures are constructed of tubes of round, oval or other appropriate cross-section from thin and hard sheet metal which hitherto could not be used for this purpose. In the hitherto known support structures composed of hollow members and tubular constructions the usual ratios between wall thickness and tube diameter of up to approximately 1-30 have been used, and material suitable for the welding or riveting is used.

In order to increase the buckling resistance while employing the same amount of material, in the case of the subject of the invention the ratio of the wall thickness to diameter of the tube is increased from 1 to 100 up to 1 to 400 and at the same time so hard a material is used that a reliable and secure connection can be achieved with the connecting means of this invention. Moreover, in order to increase the strength of parts which receive compression strains, there are used conical and spindle shaped tubes or tubes whose wall thickness increases and decreases conically or step-wise, in dependence on the increase and decrease of the required buckling strength in the individual bar.

Fig. 1 shows the cutting of two small conical tubes from one wall portion or alternatively the cutting of a relatively large conical tube from two half portions of sheet metalwithout waste of material. In dependence on the roll width which can be supplied the tube casings are cut out from one or more casing portions without If the roll width is not sufiicient for two tube divided by the number of casing portions, and the cut '1 in Fig. 1 is formed at such an inclination that the ends 2 of the casing portions, when arranged side by side,

produce the periphery of the large end of the tube, and

the ends 3 of the casing portions, arranged side by side, produce the periphery of the small end of the conical tube. If the overlapping seams of the successive tubes are to be arranged side by side and so as to be resistant to distortion, on the one hand two or more conical outer halves in Figs. 10 and 11 and on the other hand two less conical inner halves 11 of the same figures are cut from like sheet widths by a more sloping cut, and thus the production, preparation and storage is simplified.

According to the invention the cut portions are rounded and the shell portions are provided with the connecting tongues for the longitudinal seams. For the production of a round tube of cylindrical or conical form from a shell element, the two ends of the development are rolled in the form of a quadrant plus the seam overlapping, as shown in Fig. 2. Then the longitudinal edges are pro- 'vided in known manner, preferably according to Figs. 14

in Fig. 17.

For the production of like tubes having an oval crosssection or elliptical cross-section, the whole development is first rounded according to the are indicated at R, as shown in Fig. 5. Then the longitudinal edges of the development are provided with the connecting tongues 12 and 13, as shown in Fig. 6, and the development sectors 4 and 5 are subsequently curved more sharply according 'to the radius r, so that the elliptical tube according to Fig. 7 is produced. In the case of tubes for single-column masts and girders with unilaterally increased load, the elliptical cross-section compared to the circular crosssection has a unilaterally increased moment of resistance and the surface exposed to wind is reduced in the same direction.

Streamlined tubes having a very flat uniform crosssection for aircraft struts, pylons, contact line masts etc. may be produced in the same manner.

Figs. 8, 9, l0, 11 and 12 show the production of a tube from two shell halves. Fig. 8 shows a rounded shell or tube half without connecting tongues, which are to be formed subsequently, according to the invention, by an appropriate cutting tool, Fig. 9 showing the shell half with such tongues. All connecting tongues on both longi tudinal edges extend outwardly. Fig. 10 shows the other tube half in which all the connecting tongues extend inwardly. Figs. 11 and 12 show the two tube halves connected to form one round tube. It is also possible to produce any other desired cross-sectional shapes from two or more shell portions and the connecting tongues of the two edges of each shell portion may be bent out in like or inverse manner.

The preparation of the longitudinal seams is carried out according to the invention by cutting and bending upwards in arcuate form connecting tongues on the sheet metal edges which are to be connected, which then engage in one another and when the seam is closed act as counter-sunk rivets interlocking the hard material and having a longitudinal cross-section particularly resistant to shearing strain.

Seams with angularly disposed connecting tongues have previously been known which were produced by stylusshaped blades cutting vertically into the sheet surface. Metal sheets of particularly great hardness such as are desirable for the thin walls of constructional tubes and for the structure of aircraft could not be connected with such connecting tongues. The outer layer of the bending edge becomes torn. The new method of production prevents tearing.

The left-hand part of Fig. 13 shows diagrammatically a tool arranged for cutting two connecting tongues, and the right-hand part shows a tool which with the blades 15 and 16 carrying out the bending movements has just cut out from the metal sheet and bent in arcuate fashion the connecting tongues 17 and 18. The form of the patrix and of the matrix and the easy curving action of the patrix prevent the formation of a bending edge and the considerable stretching of the connecting tongues which would otherwise occur and therefore also prevents the formation of any cracks. When the seam is closed the arcuate arrangement of the connecting tongues becomes in fact more angular, as shown in Fig. 17, but

this additional shaping is carried out in a second operation and under simultaneous pressure and upsetting action, and therefore even in the case of very hard material does not cause any cracks to be formed.

The patrix is provided with parts 19 which serve as a bending mould and is provided with stroke-limiting lifting members 20 which raise the metal sheet by the height of one tongue after each operation.

The head piece carrying the cutters 15 and 16 is advantageously constructed with column guiding as a holding-down device out of which the blades project under the influence of the rams 21 and 22 only towards the end of the working stroke, and into which the blades are withdrawn by the toothed shaped ends of the rams before the holding-down action is discontinued. For circular seams a small number of blades are combined in one tool, whilst for longitudinal seams a relatively large number of blades are provided.

Figs. 14 to 17 show an improved locking seam or connection of two sheet metal edges by means of connecting tongues. Fig. 15 is a section through a metal sheet in the direction AB of Fig. 14. As described aforesaid the connecting tongues are bent out from the surface of the metal sheet in arcuate but not in angular fashion, and each double tongue 23 has two single tongues 24 disposed before and after it. The locking seam hitherto known consisted merely of like double tongues 23. Both tongues are suspended on the bridge of material 25 and the width of the tongues corresponded to the width of the material bridge, so that when subjected to tractive strain the material bridge was greatly overloaded. Therevfore the single tongues 24 are arranged between the double tongues and distribute load equally over material bridge and tongue and thus increase the overall seam strength as compared with the hitherto known locking seam. The direction in which the tongues extend is varied in order to prevent displacement of the material and to provide the same resistance in each direction. Depending on the proposed use, any desired number of single tongues 24 may be arranged between two double tongues 23. Fig. 16 shows two sheet metal edges provided with connecting tongues 23 and 24 and already pushed into one another for connection. Fig. 17 is a sectional view of the seam which has been closed by pressing, rolling or hammering.

Fig. 18 shows two conical tubes 25 and 26 which are .connected in their longitudinal direction by means of a two row circular locking seam 27. The tongues of the two rows are offset relatively to one another and the lateral distance between the tongues is greater than in the case of locking seams with one row of tongues. Stamping patterns clamped or fitted over the rounded, still opened tube ends, and provided with guide elements suitable for engaging with guide elements on the tool shown in Fig. 13 ensure the exact interengaging of the connecting tongues of the two tube ends and the desired angle between the seam plane and the axis of the tube. The cutting and bending-out of the connecting tongues is effected with a tool according to Fig. 13 with only two blades. The tube end to be treated is pushed between the patrix and the matrix as into the jaws of round-nosed pliers in such manner that the connecting tongues of the one part are directed inwards and the corresponding connecting tongues of the other part are directed outwards.

The two-row circular seam 27 must be closed before ,the longitudinal seams 28 and 29. The connecting tongues opposite the longitudinal seam must be made to inter-engage first of all and the tongues are fastened progressively to both sides. By forcing apart the sheet metal edges at the longitudinal edges thereof, the interengagement of the tongues is assisted, combined with the progressive fastening. The connecting tongues of the circular seams should be bent upwards so far that they can be pushed into one another not only laterally but also perpendicularly. If after closing of the circular seams, the longitudinal seams are also closed, the lengths of the longitudinal seams which are not provided with connecting tongues and overlap from tube 25 to tube 26 along the connecting length, are connected by additional riveting which strengthens both the circular seam and the longitudinal seam.

Fig. 19 shows two conical tubes 32 and 33 each produced from one or more shell parts according to the present invention. Their wide ends are connected by a double circular locking seam 34 and there is produced a spindle shaped tube tapering from the middle to both sides. In the zone of connection the wide tube ends are cylindrical. Otherwise the production of the longitudinal seams and the circular seam corresponds to that described in Fig. 18. The widening portion increasing towards the middle of the tube in such spindle shaped tubes is advantageously filled with a cheap and pressure-resistant material such as for example concrete, preferably in a centrifugal process The spindle shaped concrete tube so formed enables a metal tube of reduced cross-section,

drical metal tubes whose wall thickness decreases from the centre to both ends are also provided, according to the invention, with centrifuged or poured-in cores of cheap, pressure resistant material such as concrete. Production is facilitated by inserting two core halves from both ends of the tube. It is more advantageous to shrink the cylindrical metal tubes on to such separately produced cores by means of diflerential heat treatment, in order to prevent any loosening when the outer tube is subjected to relatively strong heating. For reasons of economy in weight if the place of manufacture and the place of use are far apart or if there are difficulties in transport, the adaptation of the buckling resistance of the struts to the increasing and decreasing buckling moments is effected by drawing in nipples or drawing out sleeves, whose length and wall thickness are adapted to the particular requirements. The drawing in of the the nipples or drawing up of the sleeves is carried out in a cold process or after heating of the outer tube according to the known shrinking process. Subsequent hot galvanising improves the connection between the tubes inserted into one another, as does a dip soldering.

For connection to a strengthening joint the narrow ends of the spindle shaped tube are provided with a connecting member which is fitted as a reinforcing ring 34 into the narrow end or" the thin-walled tube 33. The exterior of the ring 34 consists of a corrugation of alternate annular ridges 35 and annular recesses 36 which are shallow to begin with and become steeper towards the end of the tube. The wall of the tube 33 is forced over the annular ridges 35 into the annular grooves 36 and a clampable outer ring 3? with corresponding ridges and grooves fixes the shaped wall portion of the tube from without and at the same time exerts a strong clamping effect. Ridges and grooves may correspond to thread courses and the outer ring 37, which is closed in this case, may be screwed in the manner of a retaining nut on to the shaped re-inforced tube end.. A heated outer ring 37 acts at the same time as a shrunk ring and increases the strength of the connection. The free end of the inner ring 34 is constructed as a fixing lug with a bore 38.

Fig. 20 shows the connection of the tube ends 40 and 41 with an inner ring 42. The outer side of the inner ring begins at the left with a straight portion whose length is approximately five times the thickness of the tube wall. This is followed by an annular ridge of arcuate cross-section, the height of which is 0.5 times the thickness of the tube wall and whose chord length is approximately five times the thickness of the wall, and the said ridge then merges without a step into a groove which is also of arcuate cross-section and whose depth is approximately the same as the thickness of the tube wall and whose chord length is approximately six times the thickness of the tube wall. There then "follows without a break a ridge whose height is approximately 1.5 wall thicknesses and whose chord length is approXimately five times the thickness of the tube wall, followed by a groove whose depth is approximately the thickness of the tube wall and whose chord length is approximately six times the thickness of the tube wall. These are followed without a break 'by a ridge whose height is approximately 0.5 times the thickness of the tube wall and whose chord length is approximately five times the thickness of the tube wall. The right-hand end of the inner ring 42 is again straight and, like the beginning of the inner ring, serves to guide the shaped wall portions. 1

In the region of connection the end of the tube 41 has an open longitudinal seam without overlapping. The inner vring 42 is so large that when it is inserted it slightly widens the tube 41. The wall of the tube 41 ,is now pressed about the ridges and into the grooves. The end of the tube 40 has a diameter which is greater ilarly in roof construction. the tubes may be cylindrical, conical or spindle shaped :ring with a clamping bolt.

by two tube wall thicknesses than the tube 41 and is shaped to correspond to the tube 41. Since this tube end'also does not have a closed seam over the length sions of the ridges and grooves on both rings should be so chosen that the tube walls are clamped earlier at the flanks of the profiles than in the bottom thereof.

'A wedge action is thereby provided which even in the case of inconsiderable tension between the rings etfects a good application pressure and clamping of the tube walls up to their maximum resistance to pressure, traction and distortion.

The gradual transition from the marked deformation in the middle of the connection to a straight surface at the ends of the connection enables the strength of the tube to be fully employed whatever the nature of the particular demands.

Fig. 21 is a partly sectional view of a similar connection to that of Fig. 20. In this case the ends of the tubes to be connected adjoin one another with a small interval therebetween, and are each provided with a re-inforcing inner ring 45 and 46. The shaping of the tube ends and the type of the connection are substantially the same as in the case of Fig. 20, but in this case the middle of the connection coincides with the ends of the tubes. The

clamping outer ring is widened to the dimensions of the two inner rings and acts as a sleeve member for transmitting forces. It is also possible for connections according to Fig. 21 to be easily and rapidly assembled and dismantled at the place of assembly and in self-supporting structures by opening and closing the clampable outer ring 47. They are very suitable for use as force nodes for receiving struts, cross bearers etc.

Fig. 22 is a partly sectional view of a similar connection to that of Fig. 21. The tubes 48 and 49 are of different diameters and the inner rings are adapted to them. The clampable outer ring 50 transmitting the forces occurring is stepped in diameter in the manner of a reducing sleeve. The place of reduction is not a closed ring of material but is divided up further into stays 51 in order to make the outer ring fit closely and to enhance its tensibility.

Fig. 23 is a plan view of the right-hand side of the connection according to Fig. 22.

The outer rings 50 of Fig. 22 and 47 of Fig. 21 may also be fashioned as angled and bowed elements so that the connected tubes are then disposed at any desired angle to one another. This is often required particu- According to requirements and may be of round or elliptical cross-section.

Fig. 24 is a view of the closing of a clamping outer The left-hand end of the outer ring 53 is shaped to form a quadratic or rectangular lug 54. An auxiliary strap 52 re-inforces the lug 54 and :is fixed to the outer ring by riveting or welding. The

right-hand end of the outer ring 53 shows another constructional form. It is also shaped to form a quadratic or rectangular lug 56 and is also fashioned to form the auxiliary strap 57. An interposed bridge member 58 strengthens the lug. One or more clamping bolts 59 extend through both lugs in the direction of a tangent to the tube and the two lugs are drawn together with great force without exerting a buckling effect on the tube.

Between and at the side of the two lugs the clamping bolts may at the same time receive connecting means for struts, cross ties, etc.

Fig. is a side view and Fig. 26 is a sectional view of another clampable and detachable connection of an outer the known bolt connection.

ring to form a tube connection according to the present invention. The two identical ends of the outer ring 60 are provided on their outside surface with inclined teeth 61. A locking member 62 of appropriate arcuate shape and having inclined teeth of the same kind and size is pushed on to the toothed ends of the outer ring from the side in such manner that the teeth 61 and 63 engage in one another, and the tension in the outer ring 60 increases the further the locking member 62 is pushed on. The relief formation of the teeth holds the locking member fast. The teeth are preferably stamped. Another and still cheaper connection of the clamping outer ring 65 is shown in side elevation in Fig. 27 and in end elevation in Fig. 28. Both ends 66 and 67 of the outer ring overlap one another and are provided with ratchet teeth which fit into one another. An annular or corrugated arrangement of the teeth over the width of the outer ring prevents relatively great weakening of the material and strengthens the teeth and their mutual locking action. The end portion 66 of the ring terminates in a wedge shape and thus improves the ease with which it can be inserted and slipped into place. Additional teeth 68 and 69 at both ends of the ring facilitate the mounting of a device for drawing the ends together.

Fig. 29 is a side view of a spindle-shaped tube consisting of the conical tubes 71 and 72 assembled by means of a connection 73 of the type shown in Fig. 20. The connection 73 in the middle of the tube is used in place of the cheaper and more attractive connection 34 of Fig. -19 when struts, cross ties or the like are to be connected at this point. The small end of the conical tube 71 is connected to the small end of a likewise conical tube 74 by the connection 75 for nodes. This connection 75 corresponds to Fig. 21 and to the closure of the clamping outer ring of Fig. 24 with clamping bolts. The diagonal struts 76 and 77 are at the same time fixed by means of the said clamping bolts. In many cases such as with four-legged masts for overhead lines a further two struts off-set by relatively to the struts 76 and 77 start from the force node. The outer ring is then provided at this position with eyes and clamping bolts as in Fig. 24 for fixing the struts.

Figs. 36 and 37 illustrate the connection of two thinwalled tubes 106 and 107 which differ in diameter by the amount of the thickness of the tube wall. The tubes may be drawn, welded, riveted or constructed with locking seams. At the junction point there is provided in the interior a member 108 which has four arms 109 in the shape of a cross, the two side surfaces of each of the said arms being parallel and extending in the axial direction of the tubes. The walls of the tubes are pressed on to the arms 109 by a pressing operation and care 'must be taken, in the case of tubes with seams, that the longitudinal seam of the tube comes to be situated at the point of least deformation. Clamping members are arranged on the arms in order to strengthen the connection. In the example described four different constructions are illustrated. The tube walls 106 and 107 are pressed against one another and against the arm 109 by means of an outer clamp 111. In order to achieve a better transfer of force the parallel side surfaces of the arm 109 and the clamp portion of the clamp 111 are advantageously not smooth but are fashioned with shaped portions extending transversely to the direction in which the forces occur thus achieving a better transmission of force and an improved inter-engagement of the thin tube walls. In each of the three other fixing members a bolt 112 is used whose shank is disposed in -a bore extending through the arm 109. Owing to the fact that the bolt 112 extends twice through both tube walls 106 and 107 and clamps same, a double shearing strength and a double clamping effect are obtained which gives the connection a strength several times as great as The result of the double perforation is that the force transfer surface per bolt is doubled. In place of the bolt 112 itis possible also to use riveting in these three examples. In the left-hand example (Fig. 36) the clamping effect .is obtained by means of the bolt 112 which is inserted through the smooth wall of the bore through the arm 1'09 and the walls 106 and 107. In the lower example the bore 113 through the arm 109 is fashioned in a conical manner at either side (deep recess). Those parts of the walls 106 and 107 which come to bear on the recess portions are pressed into the conical parts by the appropriately shaped interposed discs 114. The pressure of the discs 114 results in the tube 106 adhering closely to the tube 107 and improves the conditions of force-transfer from the tube 106 to the tube 107, and vice versa. The right-hand example shows a similar constructional form, but the conical part of the bore in the arm 109 is additionally provided with concentrically arranged annular grooves 116 which taper off upwards towards the flat side. The parts 115 are shaped correspondingly, which makes it easy to deform the tube walls 106 and 107 during pressing. This type of connection affords the best possibilities of taking up force.

In the choice of the member 108 care must be taken that the largest possible part of the periphery of the tube should be clamped. It is therefore expedient to chose a a multi-armed body in the case of relatively large tube diameters. Fig. 38 shows a six-armed body 108, whilst Fig. 39 shows a three-armed body 108. No upper limit is set for the number of arms. If extremely great forces have to be transferred from one tube 'to another a plurality of clamping bolts maybe arranged on each arm.

Figs. 40 and 41 againshow' a joint between two tubes 106 and 107, within which a three-armed member 108 is disposed. Since this joint also represents a force node, to which other struts 117, 118 and 119 are connected, the clamping bolts 112 serve at the same time for fixing the said struts.

Situated in the tube end 107 is a reinforcing tube 120, which advantageously consists of softer material than the tube 107. The reinforcing tube 120 may completely replace the three-armed member 108. If the latter is omitted and the reinforcing tube is pressed together until its inner wall meets over the whole periphery, the clamping surface is increased. The aim of every connection is to have as large a clamping surface as possible, since a greater force can thereby be transferred from one tube to another. The cross arm '117 connected to the joint has an inner tube 121 as a reinforcing member. The two tubes are pressed fiat at the place of connection, and are clamped by means of the bolts 122, andin this case shaped portions may also be arranged at the clamping places transversely to the forces occurring.

The cross struts 118 and 119 are also provided at the points of connection with reinforcing members. Figs. 42 to 45 show two strut ends, Fig. 42 showing a fork-shaped end and Figs. 43-45 a plain end. The strut tube 123 has a reinforcing member 124 in its interior. The bores 125 are provided for the clamping bolts. The strut ends should only be pressed as fiat as is necessary for clamping, and at least at two sides there are left (Fig. 45), up to the strut end, and to right and left of the clamping region, reinforcing concave ridges 131. These ridges 131 advantageously project only at one side, whilst th other side of the pressed-fiat tube remains plane.

It is also possible to fashion the-reinforcing member at a joint, in the same manner as in the case of the strut ends. Fig. 46 shows a joint between two tube ends 126 and 127, the tube 126 having an inner =reinforcing tube 128 and the tube 127 having an outer reinforcing tube 129. After the insertion of the reinforcing tubes the joint is pressed fiat, so that at least two, and in the illustrated example three, clamping surfaces are produced. 130 designates the axes of clamping elements which are not shown.

Since, owing to the insertion of the reinforcing member I0 fashioned by a tube and the deformation of the tubes which are inserted in one another, there occurs no weakening of the tube or of its buckling strength, it is therefore .also possible to use this arrangement in the middle of a tube ie not at .a joint. In this way it is possible to fix cross struts at any desired place on the tube.

Fig. 30 illustrates diagrammatically the construction of a :support structure of tubes and connections in accordance with the present invention. The diameters of the individual spindle-shaped tubes at the narrow end and in the middle are approximately one to two. The greatest tube lengths which can be used economically are in the region of fifteen metres. 7

Fig. 31 shows a section taken on the line GI-I through a force node of Fig. 30. The connection of the two upright struts and 81 is according to Figs. 20 and 24. The diagonal struts 82 :and 83 are fixed to the connection by the clamping bolts 84.

The clampable outer ring consists of two parts 86 and 87, wherein at least the short portion is advantageously cast or pressed, whilst long outer rings and the inner rings may be profile bands. Gaps between the connecting lugsof the diagonal struts and the lugs of'the outer rings, which lugs have the clamping bolts extending therethrough, are filled by packing discs 88 of various thicknesses.

Fig. 32 is a side view of a similar connection including the fixing of a crossbar 90. The crossbar is embraced by a clampable outer ring 91 and is fixed by means of the clamping bolts 93 to the clamping bolts 84 and by way of the four like connecting pieces 92.

Fig. 33 shows a rivet for connecting thin metal plates according to the present invention. In this case also in the middle of the connection near the rivet shank 95 the metal sheet is considerably deformed, and the deformations or shaped'portions become less towards the end of the connection, that is: towards the edge of the rivet head, and the shaped portions are reinforced by the connecting means and are clamped into one another.

In such rivet connections the strength "thereof is no longer determined by the frictional pressure at the hole, but by the strength of the plate around the outer shaped corrugation. When the connection is subjected to tractive strain the rivet hole diameter causes no weakening. The forces occurring are transferred by the rivet head and the counterpressure plate 96, which engage in the shaped portions. The very thick shanks of such rivets may be wholly or partially perforated and formed with internal threads for receiving any kind of screw. As Fig. 34 shows, such rivets may also be countersunk.

Fig. 35 shows a bolt connection of the same kind. The overlapping sheet metal edges and 101 are so deformed between two hard plates 102 and 103 that corrugated elevations and depressions extend around the bolt hole, most strongly marked nearest the bolt hole and of the said purposes at any desired sheet metal Wall portion.

Alternatively, such boltor rivet connections may also serve for butt seams on metal plate edges, strip ends, etc. The rivet and bolt heads engaging the shaped portions, or the intermediate plates transfer traction and pressure forces of the adjoining ends completely and the connection has 100% of the strength of the sheet of material extending therethrough. At the same time transverse forces can be taken up.

A good and simple connection of the outer ring ends additional and abiao'its with a similar effect and of similar type as in Figs. 25 and 26 is produced by bending back both ends by approximately 180 with a small bending radius, whereby the bending lines deviate by approximately 3 degrees from the right angle with the longitudinal direction of the outer ring development, forming a wedge shape, and on the other side deviated by 87 and a wedgeshape interval remains between the bent-back clamping ring ends.

The associated locking member is trapezoidal in plan view. Their two ends, bent back through approximately 180 over a small bending radius, also deviate approximately 3 from the right angle with the locking member breadth and engage about the bent-back ends of the outer ring. The length of all the bent-back ends is the same and corresponds to approximately 5 times the thickness of the outer ring. As the said locking member is pushed on from the side a wedge effect is produced which causes an increase in the clamping effect in the outer ring. Wherever the clamping ring may be closed before the assembly of the tube the two ends of the clampable outer ring are bent back only 130 over a small bending radius,

as is also done with the two ends of the locking member which is adapted to be fitted overthe outer ring. The thickness of the material of the locking member must be at least as great as that of the outer ring, and the length of the bent-back ends must be the same in the case of locking member and outer ring and should correspond substantially to five times the thickness of the material. Powerful pressure on the locking member in the direction of the centre of the pipe will bring the angle by which all four inter-engaging ends are bent back to at least 180 and will produce a great clamping effect in the outer ring and the gripped material. The application of heat by way of the locking member and the outer ring provide an additional shrinking effect and an increased pressing and clamping of the deformed part of the metal plate wall.

Support structures and their connections according to the invention described hereinbefore afford very great reliability and strength while requiring a very small material expenditure, and also have a relatively small surface exposed to wind and ice. The conical and spindleshaped tubes, together with their longitudinal and transverse connections, are also produced in a very cheap manner, without waste of material and without heat treatment.

I claim: 1. A hollow supporting structure, comprising a plurality of thin-walled tubularshell members of hard sheet metal joined together and forming together a rodshaped part, said part having differently large cross sections along its length and being tapered toward both ends so as to have generally a double-conical shape, two interior bracing pieces disposed within the two hollow ends of said part and having each a profiled non-planar outer surface provided with recesses therein, and removable exterior clamping means tightly surrounding said respective ends, each of said exterior means having a profiled inner surface provided with projections substantially mating with the recesses in said outer surface and interlocking therebetween the wall of each end with said interior bracing piece to form a rigid force-transmitting node at each end of said structure.

2. A supporting structure according to claim 1, wherein at least two of said tubular sheet-metal members are axially aligned and axially overlap each other, each of said tubular members having mutually overlapping longitudinal margins and having a series of arcuate tongues and intermediate holes aligned along eachof said margins and extending transverse to said margin, said tongue projecting from said sheet metal members a distance only slightly greater than the thickness of the adjacent sheet metal member, said tongues and holes of each margin in pre re engagement wit t e r p eti e .0 d 7 5 12. tongues of the other overlapping longitudinal edge, and each of said two tubular members having a peripheral row of tongues and holes along the axially overlapping 'margin in pressure engagement with the respective holes and tongues of the peripheral row of the other member.

3. A supporting structure according to claim 1, wherein at least two of said tubular sheet-metal members are axially aligned, each of said two members being frusto- 'conical and having its end of smallest cross section directed toward one of said respective nodes and having 'its end of largest cross section joined with said other member.

4. A supporting structure according to claim 1, wherein at least two of said tubular sheet-metal members are axially aligned, each of said two members being frustoconical and having its end of smallest cross section directed toward one of said respective nodes and having its end of largest cross section axially overlapping said other member, and rigid reinforcing means joined with said two members at said axially overlapping ends, said means comprising an inner body within said two members and an outer annular piece tightly surrounding said inner body and said overlapping ends of said two members.

5. A supporting structure according to claim 1, comprising a cast core of compression-resistant material within the hollow of said part and in tight engagement therewith.

6. A supporting structure according to claim 1, wherein at least two of said tubular sheet-metal members are axially aligned, each of said two members being frustoconical and having its end of smallest cross sections directed toward one of said respective nodes and having its end of largest cross section joined with said other member, and a casting of concrete located within said members and forming a rigid core at the locations of said largest cross sections.

7. A supporting structure, comprising two hollow parts joined together in end-to-end relation, each of said parts being formed of a plurality of thin-walled tubular shell members of hard sheet metal and having differently large .cross sections along its length tapered toward both ends so as to have generally a double-conical shape, two interior bracing pieces disposed within the two hollow ends of each part and having each a corrugated outer surface, and exterior sleeve means tightly surrounding said respective ends and having a corrugated inner surface interlocking each end between said inner surface and said two corrugated outer surfaces to form a rigid force-transmitting node, one of said sleeve means being common to the two adjacent ends of said two parts and having a single sleeve body axially overlapping the two interior bracing pieces at said two ends.

8. A hollow supporting structure, comprising a plurality of thin-walled tubular shell members of hard sheet metal, said members having respective overlapping margins, each margin having a row of alternating tongues and holes in interlocking engagement with the respective holes and tongues of an overlapping margin whereby said members form together a rod-shaped .part having differently large cross sections along its length and being tapered toward both ends so 'as to have generally a double-conical shape, two interior bracing pieces disposed within'the two hollow ends of said part and having each a profiled non-planar outer surface, and exterior clamping means tightly surrounding said respective ends, each of said exterior means having a profiled inner surface substantially mating with said outer surface and interlocking the wall of each end between said inner surface and said interior bracing piece to form a rigid forcetransmitting node at each end of said structure, and one of said two pieces of at least one of said nodes having attachment means for joining said part with other structure,

9. In a supporting structure according to claim 8, one of said interior bracing pieces having a projection extending axially beyond the end of said part and forming said attachment means.

10. In a supporting structure according to claim 8, each of said profiled surfaces of said interior and exterior node pieces comprising substantially peripheral grooves, said grooves having a depth decreasing in the direction from the end toward the middle of said part.

11. In a supporting structure according to claim 8, said exterior clamping pieces having radially projecting lugs which form said attachment means.

12. In a supporting structure according to claim 8, one of said exterior clamping pieces forming a longitudinal gap and having two lugs adjacent to the respective sides of said gap, said lugs having respective bores registering with each other, a clamping bolt traversing said bores, said bores having a bolt-guiding length of at least 1.4 times the diameter of the clamping bolt, and another structure joined with said clamping piece by said clamping bolt for transmitting force to said part.

13. In a supporting structure according to claim 1, each of said exterior clamping pieces forming a split ring and having gullet teeth located on both sides .of the split gap and extending over the whole axial width of said ring, the teeth on one side of said gap being disposed at an acute angle relative to those on the other side so that said teeth together form a family of wedge lines, and an arcuate locking member extending exteriorly of said ring across said gap and having teeth in engagement with those of said ring, whereby When said locking member is pushed onto said ring from the side a wedging effect is produced to tighten said ring.

14. In a supporting structure according to claim 1, each of said exterior clamping pieces having a gap so as to form a split ring, said split ring having two ends projecting outwardly away from said gap over a length which is a multiple of the wall thickness of said exterior piece, said two ends, when relaxed, extending at an angle relative to each other and a locking member engaging said two ends and, when seated therefrom, increases said angle whereby said ring is tightened.

15. A supporting structure according to claim 1, wherein at least two of said tubular sheet-metal members are axially aligned and axially overlap each other, said two parts having one of said int rior bracing pieces in common and said bracing piece being located within the overlapping ends of said two parts, and said two parts having at least one of said exterior clamping means in common and said clamping piece being located at said common bracing piece.

16. A supporting structure according to claim 1,

wherein at least two of said tubular sheet-metal members are axially aligned and axially overlap each other, said two parts having one of said interior bracing pieces in common and said bracing piece being located within the overlapping ends of said two parts and having a sub stantially regular non-circular cross section and a plurality of surfaces extending parallel to the axis of said bracing piece, said bracing piece having bores traversing said surfaces, said exterior clamping means comprising bolts extending through said bores and each extending twice through the walls of said two overlapping parts, said bolts securing said walls against said surfaces of said interior bracing piece.

17. A supporting structure according to claim 1, wherein'at least two of said tubular sheet-metal members are axially aligned and axially overlap each other,

said two parts having one of said interior bracing pieces in common and said bracing piece being located within the overlapping ends of said two parts and having a substantially regular non-circular cross section and a plurality of surfaces extending parallel to the axis of said bracing piece, said bracing piece having bores traversing said surfaces, said exterior clamping means comprising bolts extending through said bores and each extending twice through the walls of said two overlapping parts, said bolts securing said walls against said surfaces of said interior bracing piece, and a tubular strut extending away from said clamping means in an angular direction relative to the axis of said two parts, a reinforcing member disposed in one end of said tubular strut and firmly joined therewith, said reinforcing member having flat end means projecting over said strut, and said end means being traversed by one of said bolts whereby said bolt secures said strut to said clamping means.

References Cited in the file of this patent UNITED STATES PATENTS 

